The present disclosure relates to vehicle steering systems, and more particularly to electric power steering systems.
Power steering systems, such as electric power steering (EPS), electric power assisted steering (EPAS), and motor-driven power steering (MDPS), utilize an electric motor, a torque sensor, and a steering wheel position sensor to assist an operator to maneuver a vehicle. Generally, the electric motor, the torque sensor and the steering wheel position sensor may be mounted to a steering column. The electric motor may drive a reduction gear operably coupled to the steering column to assist in column rotation.
When the operator applies a torque to the steering wheel, the torque sensor measure this torque and sends a torque signal to an electronic control unit (ECU). Similarly, the steering wheel position sensor detects the angular position of the steering wheel and sends a position signal to the ECU. The ECU applies the torque signal and the position signal along with other vehicle information, such as vehicle speed and the rate of steering wheel rotation, to calculate a desired steering assist power and send an associated command signal to the electric motor. The steering assist capability of the power steering system may include a feature that provides an active return assist that is associated with returning the steering wheel to a center position (i.e., after vehicle turn completion) based on a variety of sensory inputs to the ECU. Unfortunately, the various sensors required to provide steering assist capability, contribute toward design complexity, cost, and the weight of the vehicle.
Accordingly, it is desirable to provide a power steering system that may reduce the number of required sensors and/or components, may be more robust, may be simpler in design, and may be less costly.